Machine engines may contain water pumps that circulate coolant from a radiator to engine components such as, for example, an engine cylinder block or a power conversion unit. The coolant circulated by the water pump is used to reduce excess heat on such engine components.
Current engine water pumps may be controlled by mechanical means such as, for example, a V-belt, a serpentine belt, or a timing belt. Such mechanical connections to a water pump may limit the placement and use of a water pump in an engine. For example, a water pump being driven by mechanical means may only be able to be placed near the mechanical connection. Furthermore, a water pump driven by mechanical means may have limitations with regard to variable speed operation. For example, a water pump driven mechanically may be limited to on or off states or may be limited to operate at speeds corresponding with the speed of the engine.
To overcome some of the limitations of mechanically driven water pumps, electrical water pumps have been developed and systems have been developed that control operation of such electrical water pumps. While cooling systems employing mechanically driven water pumps often require a radiator bypass for use when engine temperatures are low (because the pump is always running if the engine is running), electrical water pumps may be controlled to decrease rotor speed or stop operating if cooling is not desired (e.g., if the temperature parameter is below a given threshold temperature). For example, U.S. Pat. No. 4,580,531 (the '531 patent) discloses a system configured to leave the water pump off, after initial startup of the engine, until the engine reaches a predetermined threshold temperature.
While the '531 patent may disclose using a delay after engine startup before turning on the electric water pump, there are other considerations related to operation of electrical water pumps that are not addressed by the '531 patent. For example, in some cases, the electrical water pump may be supplied with electric power by a generator associated with the engine. When the engine is started, the generator may take several seconds to execute an initialization procedure. During the initialization of the generator, the electric water pump may receive a reduced voltage from the generator. It may be desirable to enable the generator to initialize without any unnecessary load. Furthermore, by waiting for operating systems to reach a predetermined threshold temperature, the '531 patent may be slow to react to, and/or slow to take advantage of, changed conditions, such as increases in voltage available to the electric water pump from the generator.
The disclosed system is directed to improvements in existing cooling systems.